Electric water heater



June 19, 1945. F E, HUMMEL 2,378,772

ELECTRIC WATER HEATER Filed June 25, 1942 V2 Sheets-Sheet 1 June 19,1945- F. E. HUMMEL ELECTRIC WATER HEATER 2' sheets-sheet 2 v Filed June25, 1942 @@@QQQQQQQ Patented June 19, 1945 yUNITED STATES PATENT OFFICEELECTRIC WATER HEATER Frederick E. Hummel, Chicago, Ill.

Application June 25, 1942, Serial No. 448,333

11 Claims.

'I'he present invention relates generally to Water heaters. Moreparticularly the invention relates to that type of water heater. whichis of the electric variety and comprises a receptacle for the water tobe heated and in addition an electric heating unit which is positionedfor the most part in the receptacle directly over the bottom thereof,effects heating of the water when current is supplied to it and embodiesa copper tube with down-turned ends extending through holes in thelreceptacle bottom and a resistance element extending longitudinallythrough the tulbe and having binding posts at its ends for connection toa pair of current conductors.

One object of the invention is to provide an electric Water heater ofthis type Which, due to the construction and design of the heating unit,is an improvement upon, and more efficient than, previously designedheaters.

Another object of the invention is to provide an electric water heaterof the type under consideration in which the heating unit comprises inaddition to the tube and resistance element a jacket-type casting whichis formed of aluminum or like material having high heat conductivity,surrounds the portion of the tube that is disposed in the receptacle,and serves materially to increase the rate of heat transfer from theresistance element to the water in the receptacle to the end that theefficiency of the unit as a whole is increased and there is quick orrapid heating or boiling of the water in the receptacle when the unit isenergized by the supply of current to the element. n

Another object of the invention is to provide an electric water heaterof the last mentioned character in which the casting around the tube isso arranged and designed that it permits the water in the receptacle tocirculate readily past it and serves not only to increase the rate oftransfer of heat from the resistance element to the water but also toprotect the copper tube and prevent it from being distorted or improper-1y fiexed in connection with installation of the unit or removal of theunit from the receptacle in connection with repair or replacementthereof.

A further object of the invention is to provide an electric Water heaterof the type under consideration in which the heating unit embodies as anauxiliary part thereof a thermostatic switch which is included in one ofthe conductors for the resistance element, serves automatically tointerrupt the supply of current to the element when the water in thereceptacle reaches a dangerously low level'due to evaporation or boilingthereof, and is disposed exteriorly of the receptacle and supported'fromthe down-turned ends of the copper tube.

A still further object of the invention is to provide an electric Waterheater which is generally of new andimproved construction, effectivelyand eiliciently fulfills its intended purpose and is characterized bythe fact that the heating unit is readily removable from the receptacleand may be installed with facility.

Other objects of the invention and the various advantages andcharacteristics of the present heater will be apparent from aconsideration oi the following detailed description.

The invention consists in the several novel features which arehereinafter set forth and are more particularly dened by claims at theconclusion hereof.

In the drawings which accompany and form a part of this specification ordisclosure and in which like numerals of reference denote correspondingparts throughout the several Views:

Figure l is a vertical section of an electric Water heater embodying theinvention, parts of the heating unit being broken away and other partsbeing shown in section for illustrative pur-Y poses;

Figure 2 is ran enlarged vertical transverse section taken on the line2-2 of Figure l and showing in detail the cross-sectional design andconstruction of the casting of the heating unit;

Figure 3 is an enlarged vertical transverse section taken on the line3-3 of Figure 1 and illustrating in detail the manner in which theheating unit is removably secured in place with respect to thereceptacle bottom;

Figure 4 is an enlarged vertical transverse section taken on the line4-4 of Figure l and illustrating the design, construction andarrangement of the thermostatic switch for interrupting the ow ofcurrent to the resistance element when the unit overheats as a result ofdissipation of the body of Water in the receptacle due to evaporation orboiling;

Figure 5 is a perspective of the casting constituting a part of theelectric heating unit;

Figure 6 is a plan view of the unit, parts being broken away and otherparts being shown in section in order to show the manner in which thecasting surrounds the copper tube;

Figure 'I is a bottom view of the casting of the unit; and

Figure 8 is .an end view of the casting.

The electric heater which is shown in the drawings constitutes thepreferred form or embodiment of the invention. It is designed primarilyto heat water or other liquid and comprises a receptacle 9 and a heatingunit l0.

The receptacle 9 is adapted to hold the body of water or other liquid tobe heated and may be in any desired form. As illustrated in Figure l, itcomprises a bottom I I and a continuous side wall I2 and lhas an opentop. The side wall is suitably joined to, and extends upwardly from, themargin of the bottom and defines with the bottom a compartment orchamber for the water to be heated. The bottom Il is substantiallyimperforate and has depending legs I3 whereby the receptacle 9 is heldin an elevated position with respect to the support or surface overwhich it is disposed. If desired the receptacle and legs may be formedof sheet metal.

The heating unit I is disposed for the most part in the receptacledirectly over the bottom I I thereof and serves, when energized, to heatthe water in the receptacle. It is in the form of a unit or unitarystructure and comprises as the main parts thereof a tube I4, an electricresistance element I5, a casting I6 and a thermostatic switch The tubeI4 is formed of copper or like material having high heat conductivityand is bent centrally so that it is U-shaped so far as contour isconcerned and comprises a pair of spaced apart, parallel arm-like partI8 and a semi-circular intermediate or connecting part I9 betweencertain ends of the parts I8. 'I'he parts I8 and I9 of-the tube |4extend horizontally, as shown in Figure l, and are disposed over, and inspaced relation with, the receptacle bottom II.

The free ends of the arm-like parts I3 of the tube I4 are provided withdown-turned extremities 20 and these extend through a pair of laterallyspaced circular holes 2| in the bottom II of the receptacle. The lowerends of the down-turned extremities 20 of the tube I4 are of reduceddiameter (see Figure 3) and surround a pair of binding posts 22. Thelatter are suitably insulated from the lower ends of the extremities 20and are in the form of screw type rods 23 and clamping nuts 24 on therods. The upper portions of the down-turned extremities 20 are providedwith externally threaded copper or brass sleeves 25 and these aresoldered or otherwise fixedly secured to said upper portions of the tubeextremities 20 and extend through the holes 2|, respectively. Nuts 26are mounted on the sleeves 25 and together with the sleeves constitutemeans for removably securing the heating unit ID in place.

The resistance element I of the heating unit I0 is in the form of a finewire and extends longitudinally through the tube I4. It is suitablyelectrically insulated from the tube interior and has one end thereofconnected to the upper end of the screw type rod of one of the bindingposts 22 and its other end connected to the upper end of the rod of theother binding post. A pair of conductors 21 and 28 serve to connect theresistance element I5 to a source of electric current. The conductor 21leads and is connected to one of the binding posts 22 and the otherconductor, i. e., the conductor 28, is connectedto the other bindingpost. When current is supplied to the resistance element I5 the latterbecomes heated to a comparatively high degree and serves to heat thebody of water in the receptacle 9. The tube I4 and the casting I6function as heat transfer members and transfer the heat from theresistance element to the water. As hereinafter described, thethermostatic switch |`I is included in the conductor 21 and servesautomatically to out off the flow of current through the resistanceelement when the water in the receptacle drops to a low level due toevaporation or boiling thereof.

The casting I6 constituting part of the unit III has a twofold purpose.In the first place it serves materially to increase the radiatingsurface of the unit; and secondly, it operates to protect the tube I4and the resistance element I5 against bending or distortion duringassembly or removal of the unit with respect to the receptacle bottomII. Preferably the casting is formed of aluminum, although it is to beunderstood that instead of aluminum any other material having 'high heatconductivity may be employed. It is cast around the arm-like parts I8and the semi-circular connecting part I9 of the tube I4 and comprises apair of horizontally extending, laterally spaced, parallel arm-likeparts 29, a semi-circular part 30, a headlike part 3| and a web 32. Forpractical purposes the casting I6 is of one-piece design. The arm-likeparts 29 of the casting surround the arm-like parts I8 of the tube I4,respectively, and are approximately three times as thick as the tube.The semi-circular part 30 is disposed at one end of the casting I6. Itserves to connect together the parts 29 and surrounds the semicircularconnecting part I9 of the tube. The head-like part 3| is located at theother end of the casting and surrounds the right angle bends between thefree ends of the arm-like parts Il of the tube I4 and the down-turnedextremities 23. It is elongated transversely of the casting andpreferably has a fiat top surface. The sides and top portions of theparts 29 and 30 of the casting are curved or rounded whereas the bottomfaces or portions are flat. The web 32 extends between the inner lowerside portions of the arm-like parts 29 and at one end thereof joins thesemi-circular part 3U and at its other end joins the head-like part 3|.It is of reduced height and is coplaner with the fiat bottom surfaces ofsaid arm-like parts 29 of the casting. Holes 33 are formed ln the web 32and permit water in the receptacle to flow or circulate upwardstherethrough and thence past the other portions or parts of the casting.The semi-circular part 35 of the casting is provided on the bottomsurface thereof with a depending lug 34 and the head-like part 3| at theother end of the casting is provided with a depending marginal flange35. The lug and flange are substantially of equal height and serve aslegs for supporting the casting I6 in an elevated position with respectto the bottom II of the receptacle 9. When the heating unit I0 isenergized the portion of the water that is in the immediate vicinity ofthe casting is heated by conduction and then rises to the top of thebody of the water in the receptacle. This results in the cooler watercirculating downwards into contact with the casting I6. The portion ofthe water that is directly over the hole equipped web 32 rises. whenheated and results in additional water circulating upwards through thecasting via the holes 33. The head-like part 3| of the casting I6overlies the portion of the receptacle bottom that defines the holes 2|and is supported therefrom by way of a gasket 36. The latter nts betweensaid portion of the receptacle bottom and the lower surface of themarginal flange 35 on the head-like part 3| and operates when the nuts`26 are tightened to form a leakproof joint between the head-like part3| and the receptacle bottom whereby leakage of water under thehead-like part 3| and through the holes 2| is prevented.

Preferably the gasket 36 is shaped conformably to the ilange 35.

The thermostatic switch I1 is disposed directly beneath the receptaclebottom II and com prises an elongated open top box-like housingl and apair of vertically spaced, parallel, substantially horizontallyextending contact strips 38 and 39 in the housing. The housing is in theform of a sheet metal stamping and is provided at the ends thereof witha pair of out-turned ears 40. Such ears abut" against the bottom face ofa horizontally extending metallic plate 4I. Screws 42 extend through theears 4G and the superjacent or superencumbent portions of the plate 4Iand serve removably to secure the housing to the plate. The plate fitsagainst the bottom of the receptacle and is provided with a pair ofholes 43 for accommodating the metallic sleeves around the upperportions of the downturned tube extremities 20. The nuts 28 on thesleeves 25 bear against the hole-defining portions of the plate 4I andserve when tightened to urge the head-like part 3I of the castingdownwards and thus compress the gasket 3G between the marginal flangeand the superjacent portion of the receptacle bottom II. Tightening ofthe nuts 26 results in the heating unit la beingfirmly secured in place.When the nuts are removed from the sleeves 25 the unit may be removedfrom its operative position merely by lifting itv out of the receptacle9. The contact carrying strip 38 of the switch I1 extends directly aboveand is insulated from the bottom of the housing 31. It is disposedbeneath the strip Sil and is provided at the end thereof that isopposite its contact with a binding post 44. The latter exn tendsthrough a hole in the housing bottom and has attached thereto one partof the conductor 21. The contact equipped strip 39 is of the bimetallicvariety and is supported above the strip 38 by way of a binding post 45which extends through thabottom of the housing 31 and is connected toanother portion of the conductor 21. The strips 38 and 39 of the switchare so arranged or positioned that the contacts thereof are in engagement with one another as long as normal temperatures areencountered. When the two contacts' are in engagement, switch i1 is inits closed position with the result that current is permitted to flowthrough the resistance element I5. When the unit Iii starts to overheatas the result of substantially complete boiling away of the water in therecepacle the bimetal lic strip 39 iiexes away from the strip 33 andthus automatically opens the switch I1 and cuts on or stops the iiow ofcurrent through the resistm ance element. The switch I1 is so adjustedthat it only opens when the unit Ill starts to overheat. By reason ofthe fact that there is a metal to metal contact between the switchhousing 31 and the plate 4I `and a metal to metal contact between theplate and the sleeves 25 there is an effective conduction of heat fromthe resistance element to the interior of the switch housing 31 whenoverheating of the unit occurs. rlhe switch I1 is essentially a safetydevice and prevents the unit Ill from overheating to the point where itis likely to burn out the receptacle bottom II in the event of completeor substantially complete boiling away of the water in the receptacle.By reason of the fact that the housing 31 of the switch is in heatexchange relation with the tube I4 around the resistance element I5 theswitch responds quickly and readily to any overheating of the unit I0.Because the switch is disposed ex- Cal teriorly of the receptacle 9 itdoes not come into contact with the water in the receptacle and cor-`rosion of the parts thereof is effectively avoided. It is contemplatedthat the thermostatic switch I1 will be employed in addition to a mainswitch (not shown) In installing the unit I0 with respect to thereceptacle the nuts 26 are first removed from the sleeves 25. Thereafterthe unit is lowered into the receptacle and is so manipulated as tobring the sleeves through the holes 2l in the bottom II of thereceptacle. When the unit is in place the switch carrying plate 4I ismanipulated into place on the under side or face of the receptaclebottom and the nuts 2G are again applied to the sleeves 25 and thentightened. Tightening of the nuts, as previously pointed out, results inthe head-like part 3| of the casting being drawn towards the receptaclebottom into a position wherein the gasket 3S is in a compressed or sealestablishing position and the unit I0 is clamped or locked in place.After tightening of the nuts 26 the electrical conductors 21 and 28 areapplied to the various binding posts so as to complete the electricalcircuit for the resistance element I5 of the heating unit Hl. When it isdesired to heat the body of water or other liquid in the receptacle 9the main switch is closed by the operator.' This results in currentflowing through the resistance element I5 and the resulting heat beingtransferred through the copper tube I4 and the aluminum casting I6 tothe water, As soon as the unit starts to generate heat the water in thereceptacle circulates around the casting 'in the manner heretoforedescribed and becomes heated as the result of contact with the outersurface portions of the casting. A portion of the water in thereceptacle circulates upu ward through the holes 33 in the web 32whereas other portions circulate past the side faces of the parts 29 and30. Should the water in the receptacle boil away or the level thereofdrop to a dangerously low point in the receptacle the thermostaticswitch I1, as hereinbcfore pointed out,

operates immediately upon overheating of the` unit I0 to cut 01T theflow of current through the resistance element I5. Should it be desiredto remove thel unit I8 for inspection or replacement purposes it is onlynecessary to disconnect the conductors 21 and 28 and then remove thenuts 26 from the sleeves 25. As soon as the nuts are removed the unitmay be removed from the receptacle by lifting it from the bottom II.

The herein described water heater is extremely eiicient and may be builtat a comparatively low cost due to the simplicity of the heating unitI0. It has a comparatively long life and operates quickly to heat to theboiling point the water or other liquid in the receptacle by reason ofthe fact that the heating unit includes the aluminum casting I6 aroundthe copper tube I4. In practice it has been found that a heater having aheating unit of the type hereinbefore specifically described will heatthe body of water in the receptacle faster and with less current inputthan a heater wherein the heating unit includes no aluminum castingaround the copper tube.

The invention is not to be understood as re stricted to the details setforth since these may be modied within the scope of the appended claimsWithout departing from the spirit and' scope of the invention.

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid heater comprising a receptacle for the liquid to be heatedand a heating unit disposed for the most part in the receptacle and overthe bottom thereof and embodying a U-shaped metallic tube having theends thereof communicating with the receptacle exterior, an electricresistance element extending longitudinally through the tube and havingits ends terminating exteriorly of the receptacle and provided withmeans for connection to current conductors, and an elongated separatelyformed jacket in the form of a casting of metal having high heatconductivity extending around and engaging the tube and having dependinglegs at its ends for supporting it in spaced relation with thereceptacle bottom.

2. A liquid heater comprising a receptacle for the liquid to be heated,and a removable heating unit disposed for the most part in thereceptacle and over the bottom thereof and embodying a metallic tubehaving separated downturned ends' extending through the receptaclebottom, an electric resistance element extending through the tube andhaving its ends terminating adjacent the tube ends and provided withmeans for connection to current conductors, a separately formed jacketin the form of a casting oi material having high heat conductivityextending around and engaging only the portion of the tube within thereceptacle, and releasable clamping means carried by the downturned endsof the tube and serving to maintain the portion of the casting adjacentsaid downturned ends in clamped relation with the subjacent portion ofthe bottom of the receptacle.

3. A liquid heater comprising a receptacle for the liquid yto be heatedand a heating unit disposed for the most part in the receptacle and overthe bottom thereof and embodying a U-shaped metallic tube having theends thereof communicating with the receptacle exterior, an electricresistance element extending longitudinally through the tube and havingits ends terminating exteriorly of the receptacle and adapted for conHnection to current conductors, and a casting of material of high heatconductivity spaced from the receptacle bottom and including a U-shapedpart extending around and engaging the tube, and a web extending acrosssaid U-shaped part and having a longitudinal series of holes therein.

4. A liquid heater comprising a receptacle for f the liquid to be heatedand a heating unit disposed for the most part in the receptacle and overthe bottom thereof and embodying a U-shaped metallic tube having theends thereof communicating with the receptacle exterior, an electric`resistance element extending longitudinally through the tube and havingits ends terminating exteriorly of the receptacle and provided withmeans for connection to current conductors, and a separately formedjacket inthe form oi a onepiece casting of material having high heatconductivity cast around the tube and embodying a U-shaped partextending around the tube and having an opening in the central portionthereof and a head-like part connected to, and extending between, theends of the U-shaped part and serving to cross connect the ends of thetube.

5. A liquid heater comprising a receptacle for the liquid to be heatedand a heating unit disposed for the most part in the receptacle and overthe bottom thereof and embodying a U-shaped metallic tube having theends thereof communicating With the receptacle exterioran electricresistance element extending ,longitudinally through the tube and havingits ends terminating exteriorly ast/8,772

of the receptacle and provided with means for connection to currentconductors, and a separately formed jacket in the form of a casting ofmetal having high heat conductivity and embodying a U-shaped partextending around and engaging the tube and having a depending leg forsupporting it in spaced relation with the receptacle bottom and alsohaving an opening in the central portion thereof, and a head-like partextending between, and connected to, the ends of the U- shaped part,serving to cross connect the tube ends and having a. depending leg forsupporting it in spaced relation with the receptacle bottom.

6. A liquid heater comprising a receptacle for the liquid to be heatedand a heating unit disposed for the most part in the receptacle and overthe bottom thereof and embodying a. U-shaped metallic tube having theends thereof communicating with the receptacle exterior, an electricresistance element extending longitudinally through the tube and havingits ends terminating exteriorly of the receptacle and provided withmeans for connection to current conductors, and a jacket in the form ofa casting of metal having high heat conductivity embodying a U-shapedpart extending around and engaging the tube, a head-like part adjacentthe tube ends and a web extending across the U-shaped part and providedwith a longitudinal series of holes therein, and also embodyingdepending legs on the U-shaped part and the head-like part forsupporting it in spaced relation with the receptacle bottom.

'7. A liquid heater comprising a receptacle for the liquid to be heatedand a removable heating unit disposed for the most part in thereceptacle and over the bottom thereof and embodying a U-shaped metallictube disposed in a substantially horizontal position in the receptacleand having down-turned extremities aligned with, and extending through,holes in the receptacle bottomy an electric resistance element extendinglongitudinally through the tube and having its ends extending throughthe holes in, and terminating exteriorly of, the receptacle bottom andadapted for connection to current conductors, a separately formed jacketin the form of a casting of metal having high heat conductivity,embodying a U-shaped part extending around and engaging the tube andhaving an opening in the central portion thereof and a head-like partbetween, and connected to, the ends of the U- shaped part and extendingaround, and serving to cross connect, the bent portions of thedownturned extremities of the tube, and releasable clamping meansdisposed exteriorly of the receptacle and carried by said down-turnedextremities for urging said head-like part of the jacket into clampedrelation with the subjacent portion oi the receptacle bottom.

8. A liquid heater comprising a receptacle for the liquid to be heatedand a removable heating unit disposed for the most part in thereceptacle and over the bottom thereof and embodying a. metallic U-shaped tube disposed in a substantially horizontal position in thereceptacle and having down-turned extremities extending through holes inthe receptacle bottom, an electric resistance element extendinglongitudinally through the tube and having its ends terminating adjacentthe ends of the tube extremities and provided with means for connectionto current conductors, a jacket for the tube in the form of an elongatedhorizontally extending casting of metal having high heat conductivelyembodying a U-shaped part extending around and engaging the tube, a

head-like part extending around the bent upper ends of the tubeextremities and a marginal depending iiange-like leg on the head-likepart for spacing the head-like part and the U-shaped part from thereceptacle bottom, and releasable clamping means carried by thedown-turned extremities of the tube at a point beneath the receptaclebottom for urging the head-like part and leg of the casting in clampedrelation with the subjacent portion of the receptacle bottom.

9. A liquid heater comprising -a receptacle for the liquid to be heated,a heating unit disposed for the most part in the receptacle and over thebottom thereof and embodying a metallic tube having down-turned endsextending through the receptacle bottom, and an electric resistanceelement extending longitudinally through the tube and having its endsterminating adjacent the tube ends, a metallic plate mounted beneath thereceptacle bottom and on the ends of the tube and in direct contact withthe tube ends, and means for supplying current to the resistance element comprising a pair of conductors connected in connection with aliquid heater and comprising a one-piece casting formed of metal havinghigh heat conductivity and embodying a U- shaped part, a head-like crosspart at the open end of the U-shaped part, and an intermediate webwithin said U-shaped part and provided with a longitudinally extendingseries of holes, and an electric resistance element extendinglongitudinally through the U-shaped part of the casting and having theends thereof leading through the head-like part.

l1. An electric heating unit adapted for use in connection with a liquidheater and comprising a U-shaped metallic tube having the endextremities thereof angularly disposed, an electric resistance elementextending through the tube, and a, separately formed jacket in the formof a casting of metal having high heat conductivity and embodying aU-shaped part extending around and engaging the tube, a head-like crosspart extending across the free end of the U-shaped part and around thebends adjacent the inner ends of the angularly disposed end extremitiesof the tube, and an intermediate web within said U-shaped part andprovided with a longitudinal series of holes.

FREDERICK E. HUMMEL.

longitudinally

